1. Field of the Invention
The present invention relates to a method for replacing cutters, such as roller cutters and cutter bits, of a tunnel-excavating machine; a method for excavating a tunnel; and a tunnel-excavating machine, such as a tunnel-boring machine or a shield machine.
2. Description of Related Art
A tunnel-boring machine for excavating a tunnel in rock strata, which is one example of the tunnel-excavating machine, includes a cylindrical machine body; a cutterhead attached rotatably to a front portion of the machine body; a number of disc cutters and cutter bits attached to the cutterhead; a gripper located behind the machine body and adapted to grip an existing tunnel wall under pressure; and a plurality of thrust jacks extending between the machine body and the gripper. While the gripper bears a reaction force arising from excavation, the thrust jacks are extended while the cutterhead is rotating, to thereby advance the machine body. As a result, the disc cutters and the cutter bits fracture a rock formation located ahead, thereby excavating a tunnel.
A recent tendency toward an increase in the length of a tunnel to be excavated involves wear of disc cutters and cutter bits attached to the cutterhead in the midst of excavation of the tunnel. Since worn disc cutters and cutter bits cause an impairment in excavation efficiency, excavation operations must be halted in order to replace the worn disc cutters and cutter bits. Conventionally, when disc cutters and cutter bits are to be replaced, ground located ahead is stabilized through injection of chemical liquid or through freezing. When excavation progresses to the ground-stabilized point, the tunnel-boring machine retreats, and muck is removed from inside a chamber of the machine. Then, workers enter a space located ahead of the cutterhead and the chamber in order to replace the disc cutters and cutter bits.
However, this replacement operation involves the cost of chemical liquid used to stabilize ground and is thus uneconomical. Furthermore, the replacement operation consumes a relatively long period of time, thereby impairing work performance. Since workers work within a narrow work space, such as a space located ahead of the cutterhead and a space within the chamber, restrictive work conditions increase a burden on workers. To cope with this problem, a tunnel-excavating machine enabling replacement of cutter bits within an machine body is disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) No. 280878/1998.
The tunnel-excavating machine disclosed in Japanese Patent Application Laid-Open (Kokai) No. 280878/1998 is configured in the following manner. A cutterhead is rotatably attached to a front portion of a skin plate. A guide rail is disposed on the cutterhead such that an end portion of the guide rail located toward the center of the cutterhead is bent toward the interior of the machine. A plurality of holders which are connected to one another in a bendable manner are movably supported by the guide rail. The holders carry the corresponding cutter bits. A cutter bit replacement chamber is attached to the end portion of the guide rail via a gate mechanism. Each of the cutter bits can be moved into the cutter bit replacement chamber by means of a moving jack so as to replace the cutter bit with new one therein.
Generally, a plurality of cutter spokes are radially disposed on the front face of a cutterhead. A number of cutter bits are attached to each of the cutter spokes. In the tunnel-excavating machine disclosed in the above-mentioned publication, the guide rails are mounted on the corresponding cutter spokes, and the cutter bits are movably attached to the guide rails. When the cutter bits are to be replaced, each is moved into the cutter bit replacement chamber attached to an end portion of the corresponding guide rail and is then replaced with a new cutter bit therein. Since each of the cutter spokes (guide rails) must be equipped with the cutter bit replacement chamber and the moving jack, the machine structure becomes complex. Also, since the cutter bit replacement chambers are located proximity to each other, workers suffer inconvenience in replacing cutter bits. It is conceivable that the cutter bit chamber and the moving jack may be attached only to the guide rail which carries cutter bits to be replaced. However, this involves attachment and detachment of the cutter bit replacement chamber and the moving jack to and from each of the guide rails, resulting in low work efficiency.
Meanwhile, a tunnel-excavating machine advances while a cutterhead is rotated, thereby fracturing by means of cutter bits a stratum located ahead and thus excavating a tunnel. Thus, muck is present between the cutterhead and an excavation face. In the case of the tunnel-excavating machine disclosed in the above-mentioned publication, worn cutter bits are moved along the guide rail mounted on the corresponding cutter spoke and into the cutter bit replacement chamber attached to an end portion of the guide rail, and are then replaced with new cutter bits therein. Muck which accompanies excavation enters the guide rail and hinders movement of cutter bits along the same at the time of cutter bit replacement.
When worn cutter bits located on the front face of the cutterhead are moved into the cutter bit replacement chamber along the guide rail for replacement with new cutter bits, an empty space is formed in the guide rail. Since muck enters the empty space, when new cutter bits are to be returned along the guide rail to a predetermined position on the cutterhead, the filling muck hinders the return of the new cutter bits.
Also, since an opening is formed in the cutterhead in order to allow cutter bits to move from the front face of the cutterhead into the cutter bit replacement chamber located inside the machine body, muck enters the guide rail through this opening to hinder movement of cutter bits.
An object of the present invention is to solve the above-mentioned problems, and to provide a method for replacing cutters of a tunnel-excavating machine which facilitates cutter replacement operations and enables quick cutter replacement operations to thereby lessen burden imposed on workers and improve safety and work efficiency.
Another object of the present invention is to provide a method for excavating a tunnel which employs the method for replacing cutters.
Still another object of the present invention is to provide a tunnel-excavating machine which employs the method for replacing cutters.
To achieve the above object, the present invention provides a method for replacing cutters of a tunnel-excavating machine in which a plurality of columns of cutters connected one another are disposed on a front face of a cutterhead and which allows a column of cutters to be withdrawn into a machine body, the method comprising the steps of: withdrawing a column of cutters or a portion of the column of cutters into a cutter accommodation box supported by the machine body; replacing the cutters with other cutters; fixing a column of newly-loaded cutters at a predetermined position on the front face of the cutterhead; rotating the cutterhead until another column of cutters faces the cutter accommodation box; and repeating the withdrawing step, the replacing step, the fixing step, and the rotating step for sequential replacement of remaining columns of cutters.
Thus, all cutters can be replaced by means of a single set of the cutter accommodation box and a moving jack, thereby improving the efficiency of cutter replacement operations.
The present invention further provides a method for excavating a tunnel, comprising the step of replacing worn cutters with new cutters or replacing cutters with appropriate cutters according to geological ground conditions, by use of the above-described method for replacing cutters of a tunnel-excavating machine, so as to perform tunnel-excavating operations continuously.
Since tunnel-excavating operations can be performed continuously, the efficiency of tunnel-excavating operations is improved.
The present invention further provides a method for replacing cutters of a tunnel-excavating machine in which a cutterhead is rotatably attached to a front portion of a machine body; a plurality of guide rails are radially disposed on a front face portion of the cutterhead; a movable block having a cutter pivotably attached thereto is movably supported along each of the guide rails; the machine body is equipped with a single cutter accommodation box; and cutter-moving means for withdrawing the cutter into the cutter accommodation box or pushing out the cutter from the cutter accommodation box is provided; the method comprising the steps of: rotating the cutterhead to a predetermined angular position; engaging the cutter accommodation box with an end portion of the guide rail which faces the cutter accommodation box; withdrawing the cutter into the cutter accommodation box from the guide rail by use of the cutter-moving means; replacing the cutter with another cutter; pushing out the newly-loaded cutter into the guide rail at a predetermined position; and disengaging the cutter accommodation box from the end portion of the guide rail.
Thus, all cutters can be replaced by means of a single set of the cutter accommodation box and the moving jack, thereby improving the efficiency of cutter replacement operations.
Preferably, each of the cutters is a roller cutter or a cutter bit, so that a column of roller cutters or a column of cutter bits can be withdrawn into the cutter accommodation box. The method of the invention for replacing cutters of a tunnel-excavating machine can be applied to a tunnel-boring machines capable of excavating rock strata or a shield machine capable of excavating poor ground strata.
Preferably, the cutters include roller cutters and cutter bits; a column of roller cutters and a column of cutter bits are disposed in parallel on the front face of the cutterhead; and either a column of roller cutters or a column of cutter bits, or both can be concurrently withdrawn into the cutter accommodation box. The method of the invention for replacing cutters of a tunnel-excavating machine can be applied to a tunnel-excavating machine capable of excavating rock strata and poor ground strata and enables quick replacement of roller cutters and cutter bits.
The present invention further provides a tunnel-excavating machine comprising: a cylindrical machine body; a propelling jack for advancing the machine body; a cutterhead attached rotatably to a front portion of the machine body; cutterhead drive means for rotating the cutterhead; a guide rail disposed radially on a front face portion of the cutterhead; a movable block supported movably along the guide rail; a cutter attached to the movable block; a gate mechanism disposed at an end portion of the guide rail located toward the center of the cutterhead; a cutter accommodation box supported by the machine body and adapted to be engaged with or disengaged from an end portion of the guide rail via the gate mechanism; cutter-moving means for withdrawing the movable block equipped with the cutter into the cutter accommodation box from the guide rail or pushing out the same from the cutter accommodation box to the guide rail; a connection member for removably connecting the cutter-moving means to the movable block; and muck discharge means for discharging muck produced through excavation by the cutterhead to the exterior of the machine body.
Thus, cutters can be replaced easily by means of the cutter accommodation box and the moving jack, thereby improving the efficiency of cutter replacement operations. Also, the machine structure can be simplified.
Preferably, a plurality of guide rails are disposed, and the cutter accommodation box can be selectively and removably engaged via the gate mechanism with an end portion of any one of the guide rails which faces the cutter accommodation box as a result of rotation of the cutterhead to a predetermined angular position. In this case, all cutters can be replaced by means of a single set of the cutter accommodation box and the moving jack.
Each of the cutters may be a roller cutter or a cutter bit. In this case, a movable block equipped with the roller cutter or a movable block equipped with the cutter bit is movably supported along guide rails which are disposed in parallel on the front face portion of the cutterhead, and either the movable block equipped with the roller cutter or the movable block equipped with the cutter bit can be withdrawn into the cutter accommodation box. The tunnel-excavating machine of the invention can serve as a tunnel-boring machine capable of excavating rock strata or as a shield machine capable of excavating poor ground strata.
Alternatively, the cutters may include roller cutters and cutter bits. In this case, a movable block equipped with the roller cutter and a movable block equipped with the cutter bit are movably supported along corresponding guide rails which are disposed in parallel on the front face portion of the cutterhead; and either the movable block equipped with the roller cutter or the movable block equipped with the cutter bit, or both can be withdrawn into the cutter accommodation box. The tunnel-excavating machine of the invention can serve as a tunnel-excavating machine capable of excavating rock strata and poor ground strata and enables quick replacement of roller cutters and cutter bits.
Preferably, the cutter-moving means includes a moving Jack having a drive rod extending through the cutter accommodation box, and an end portion of the drive rod can be removably connected to the movable block by means of the connection member. In this case, a cutter can be easily withdrawn into the cutter accommodation box through extension/retraction of the moving block and connection/disconnection of the connection member.
Preferably, the tunnel-excavating machine further comprises cutter-accommodation-box-moving means for moving the cutter accommodation box between an engagement position, where the cutter accommodation box is engaged with an end portion of the guide rail, and a retreat position located a predetermined distance away from the end portion. In this case, engagement and disengagement between the end portion of the guide rail and the cutter accommodation box can be smoothly performed.
Preferably, a plurality of movable blocks are connected one another in a bendable manner and are movable along the guide rail, and the movable blocks equipped with the corresponding cutters are individually withdrawn into the cutter accommodation box for individual replacement thereof. In this case, the size and weight of the cutter accommodation box can be reduced, thereby increasing space within the machine body.
Preferably, a plurality of movable blocks are connected one another in a bendable manner and are movable along the guide rail, and the movable blocks equipped with the corresponding cutters are all withdrawn into the cutter accommodation box for concurrent replacement thereof. In this case, the movable blocks can be withdrawn into and pushed out from the cutter accommodation box at a time, thereby improving performance of cutter replacement operations.
Preferably, at least two parallel guide rails are disposed on the cutterhead; a first movable block equipped with a roller cutter and a second movable block equipped with a cutter bit are movably supported along each of the guide rails; and the machine body is equipped with a first cutter accommodation box for accommodating the first movable block equipped with a roller cutter and a second cutter accommodation box for accommodating the second movable block equipped with a cutter bit. In this case, both the roller cutter and the cutter bit can be replaced.
The present invention further provides a tunnel-excavating machine comprising: a cylindrical machine body; a propelling jack for advancing the machine body; a cutterhead attached rotatably to a front portion of the machine body; cutterhead drive means for rotating the cutterhead; a guide rail disposed on a front face portion of the cutterhead in such a manner as to extend radially from a center portion of the cutterhead: a movable block supported movably along the guide rail; a cutter attached to the movable block; a cutter accommodation box connected to an end portion of the guide rail located toward the center of the cutterhead; a gate mechanism for establishing or shutting off communication between the guide rail and the interior of the cutter accommodation box; cutter-moving means disposed on the cutterhead in opposition to the guide rail with respect to the center of rotation of the cutterhead and adapted to withdraw the movable block equipped with the cutter into the cutter accommodation box from the guide rail or pushing out the same from the cutter accommodation box to the guide rail; a connection member for removably connecting the cutter-moving means to the movable block; and muck discharge means for discharging muck produced through excavation by the cutterhead to the exterior of the machine body.
Thus, there is no need to dispose a plurality of cutter accommodation boxes, thereby simplifying the structure of the machine. Cutters can be replaced easily without involvement of connection/disconnection of the cutter accommodation box and the moving jack. As a result, cutter replacement operations can be completed within a short period of time, thereby alleviating burden imposed on workers with a resultant improvement in safety and work efficiency.
Preferably, the cutter-moving means includes a moving jack having a drive rod extending through the cutter accommodation box, and an end portion of the drive rod can be removably connected to the movable block by means of the connection member. In this case, a cutter can be easily withdrawn into the cutter accommodation box through extension/retraction of the moving block and connection/disconnection of the connection member.
Preferably, a plurality of the movable blocks are connected one another in a bendable manner and are movable along the guide rail, and the movable blocks equipped with the corresponding cutters are individually withdrawn into the cutter accommodation box for individual replacement thereof. In this case, the size and weight of the cutter accommodation box can be reduced, thereby increasing space within the machine body.
Alternatively, a plurality of the movable blocks are connected one another in a bendable manner and are movable along the guide rail, and the movable blocks equipped with the corresponding cutters are all withdrawn into the cutter accommodation box for concurrent replacement thereof. In this case, the movable blocks can be withdrawn into and pushed out from the cutter accommodation box at a time, thereby improving performance of cutter replacement operations.
Preferably, in the above-described method for replacing cutters of a tunnel-excavating machine, at least in the course of excavation effected through rotation of the cutterhead and in the course of withdrawal of a column of cutters into the cutter accommodation box, a lubricant is injected into a guide zone where the guide rail guides a column of cutters. In this case, since entry of muck into the guide zone is prevented, a column of cutters is smoothly moved along the guide rail, thereby improving work performance.
Preferably, in the above-described method for replacing cutters of a tunnel-excavating machine, a filler is injected into space which is formed in the guide rail as a result of movement of the cutter toward the cutter accommodation box. In this case, since entry of muck into the guide rail is prevented, a column of newly loaded cutters can be smoothly returned to a predetermined position in the guide rail without involvement of obstruction by muck, thereby improving work performance.
Preferably, the above-described tunnel-excavating machine further comprises lubricant injection means for injecting a lubricant into a guide zone where the guide rail guides the movable block. Since entry of muck into the guide zone is prevented, a column of cutters is smoothly moved along the guide rail, thereby improving work performance.
Preferably, in the above-described tunnel-excavating machine, a plurality of the lubricant injection means are disposed longitudinally along the guide rail. A column of cutters can be smoothly moved over the entire range of the guide rail.
Preferably, the above-described tunnel-excavating machine further comprises filler injection means for injecting a filler into space which is formed in the guide rail as a result of movement of the movable block toward the cutter accommodation box. In this case, since entry of muck into the guide rail is prevented, a column of newly loaded cutters can be smoothly returned to a predetermined position in the guide rail without involvement of obstruction by muck, thereby improving work performance.
Preferably, in the above-described tunnel-excavating machine, a plurality of the filler injection means are disposed longitudinally along the guide rail. In this case, a column of cutters can be smoothly moved over the entire range of the guide rail.
Preferably, in the above-described tunnel-excavating machine, when the movable block is returned to the guide rail by the cutter-moving means, a filler which fills space formed in the guide rail can be pushed out to the exterior of the guide rail. In this case, there is no need to collect the filler, and a column of cutters is smoothly moved along the guide rail, thereby improving work performance.
Preferably, the above-described tunnel-excavating machine further comprises a shutoff member connected to the movable block equipped with the cutter and adapted to close an opening portion, through which the movable block is withdrawn into the cutter accommodation box, when the movable block is located on the front face portion of the cutterhead. In this case, since in the course of excavation effected through rotation of the cutterhead, entry of muck into the machine body through the opening portion is prevented, tunnel-excavating operations can be favorably performed.
Preferably, in the above-described tunnel-excavating machine, the shutoff member is a cutter. When the cutter is to be withdrawn into the cutter accommodation box, the cutter may be moved back and forth in the vicinity of the opening portion so as to remove muck caught between the opening portion and the cutter, thereby enabling smooth withdrawal of the cutter into the cutter accommodation box.